The term ‘proficiency testing’ is one that every accredited calibration laboratory is quite familiar with. In basic terms it refers to a method of evaluating how well a laboratory is doing a particular calibration with respect to its claimed measurement uncertainty and how it fares with other participants.
Why leak test? Leak testing is performed to ensure that when in service, the component or assembly has zero leakage or a leakage that is acceptable over time for the fluid/gas that it is meant to contain, or conversely to prevent material on the outside from leaking in.
Some years ago I wrote about the ‘digital disease’ and how too many people actually believed digital displays with millionths of an inch resolution when the device they were part of could not deliver results worthy of the last few digits.